I did a search online and you can find reviews pretty easily. But are you sure that you do enough volume to justify owning a machine? Once you find a machine you like, do a "break even" analysis. Let's say the machine costs $5,000 and right now you pay $2 per t-shirt to silk screen. Yo would have to sell 2,500 t-shirts ($5,000/$2.50) to break even.
Maybe you could design a tee-shirt for my not-for-sale yet invention. . .
A bicycle seat for gay guys that has a built-in big dildo that is terrific for those bumpy rides.